NEW YORK (CBSNewYork) — New York CitySchools Chancellor Dennis Walcott said Thursday he’s hopeful that a missing 14-year-old autistic boy from Queens will be found safe.

Police and volunteers have stepped up the search for Avonte Oquendo, who has been missing for nearly a week. He was last seen Friday on surveillance video leaving the Center Boulevard School in Long Island City. The reward for his safe return was raised to $10,000, CBS 2’s Andrea Grymes reported.

“We’re still extremely hopeful and we want to make sure we find this child,” Walcott said.

Also on Thursday, the teen’s mother, Vanessa Fontaine, reached out to the public for help.

“I’m just hoping he’s okay. He finds some shelter from the rain. He’s not sick. He’s not passed out from not eating. It’s been days and days and days,” Fontaine told Grymes on Thursday.

On Wednesday, the Oquendo family filed a claim to sue the city and the school district for failing to properly supervise the teen.

“The child’s grandmother spoke to a security guard when she came to the school several hours later,” said the family’s attorney, David Perecman. “The security guard told her that the child was leaving school and she said, ‘Where are you going?’ He doesn’t speak and the child said nothing. And she let him leave.”

The missing teen’s mother said she’s upset about the surveillance video that shows her son strolling off unabated.

“I can’t watch it. I can’t see him run off like that and nobody’s running behind him to say, ‘hey kid come back here.’ There’s no one,” Fontaine said.

Perecman also said it took the school too long to notify the boy’s mother about his disappearance.

“The school had ordered a lockdown and was looking for the child in the school for an hour before they even let mom know,” he said.

Walcott said Avonte, who cannot communicate verbally, was assigned to a group of six special needs kids who are supervised by one teacher and one paraprofessional.

He could not confirm that the teen was confronted by a security guard before leaving the school.

“We’ll take a look at what the procedures are,” Walcott said. “We’re confident in our procedures, but in this particular case, it did not work. We’re going to see what happened in conjunction with the Police Department.”

On Tuesday, police thought they found Avonte in East Harlem. But when relatives arrived at the hospital, they realized the boy who had been found wasn’t Avonte.

“We’re staying strong. We’re visualizing finding my brother,” Daniel Oquendo said Wednesday. “No leads as of now, so we’re just trying to start from scratch and go any way we can.”

Police said the young man they found in East Harlem had been missing since Tuesday morning. His identity was not released.

Avonte has a fascination with trains, so the search has been focused on the mass transit system.

Avonte Oquendo, 14, was last seen leaving school on Friday, October 4. (credit: NYPD)

He is 5-foot-3 and weighs 125 pounds. He was last seen wearing a gray striped shirt, black jeans and black shoes.

“If you see him, please, please, call 911 or take him to a police station,” Fontaine said.

Anyone with information was asked to contact NYPD Crime Stoppers at 800-577-TIPS, visit the Crime Stoppers website or text tips to 274637 (CRIMES) and enter TIP577.